Why does the foam break into pieces (disperse) when I add the medium?

The reason for dispersion could be one of the following:

1. The silk solution has been standing at room temperature too long after thawing. The silk solution should be used directly after thawing (within 1 h). If the solution looks milky, do NOT spin/centrifuge the Biosilk solution as that will damage the product. 

2. The foam is not pipetted well enough. A soggy foam is more difficult to stabilize. Make sure to pipet 22-25 times with rapid speed while spreading the foam to a diameter of 0.7-1.0 cm with circular motions. However, do not over-pipet (more than 25 times) since that could result in a breakdown of the 3D structure formed. Avoid generating too large bubbles because it will give a less fibril structure. During foam formation, try to generate small and evenly distributed bubbles.

3. The ratio of the total added Biolaminin + cell suspension volume to the Biosilk volume used has been higher than 1/5. If the ratio is exceeded, the Biosilk will be too diluted to be able to generate a stable scaffold. If the cells will be mixed in after the foam has been generated, do not use more than 4 µL of the cell suspension to 20 µL of Biosilk or Biosilk 521 solution. If another Biolaminin isoform will be added to the Biosilk, the total added Biolaminin volume should not exceed 1/10 of the Biosilk volume.

4. The stabilization temperature has been lower than 37°C. Try only using the outer wells of the plate so that the stabilization temperature reaches 37°C faster. Alternatively, the stabilization time was not long enough (less than 20 min). Prolong the incubation time to 25 min.

5. When adding the medium to the stabilized foam, carefully drop the medium both on top of the foam and around it. Adding medium only around the foam will have a lifting force to the foam.